espanolAntecedentes: la literatura odontologica demuestra que los tratamientos endodonticos fallidos, comunmente son debidos a la persistencia de los microorganismos. Una caracteristica importante de los cementos obturadores de canales es su habilidad para penetrar en los tubulos dentinarios, logrando asi un sellado impermeable entre las paredes dentinarias y el material de obturacion central, reduciendo las filtraciones potenciales y aumentando la resistencia a la fractura. Objetivo: Evaluar mediante microscopia electronica de barrido (MEB) la penetracion de MTA Fillapex, cemento de Grossman (CG) y top seal a lo largo del conducto radicular. Materiales y metodos: Estudio experimental in vitro, en 36 dientes premolares humanos divididos aleatoriamente en 3 grupos, (n= 12), los cuales fueron preparados con tecnica endodontica Step Back. Cada grupo se dividio en 2 subgrupos utilizando como irrigante NaOCl al 2,5%, al igual que NaOCl al 2,5% + EDTA al 17%. Los canales fueron obturados con tecnica de condensacion lateral, seccionados longitudinalmente para observar mediante microscopia electronica de barrido a nivel de los tercios cervical, medio y apical, la penetracion del cemento al interior de los tubulos dentinarios. Se realizo analisis estadistico con SPSS v 22 IBM con p Resultados: Mediante la prueba Kruskal-Wallis, los cementos de Grossman y top seal al utilizar NaOCl + EDTA presentaron valores de p= 0,025 y p= 0,002 en los tercios medio y apical respectivamente. La prueba de Mann Whitney mostro un valor p= 0,031 en el tercio apical para el cemento MTA Fillapex al utilizar NaOCl. Los valores de la mediana fueron MTA Fillapex tercio medio= 2,0000, tercio apical= 1,0000; top seal tercios medio y apical= 4,0000; cemento de Grossman tercios medio y apical= 4,0000. Al ser igual el valor de la mediana entre los cementos top seal y Grossman se utilizaron los valores de la varianza con un resultado estadisticamente significativo para el cemento de Grossman= 0,276 en el tercio medio y top seal= 0,176 en el tercio apical. La prueba de Mann Whitney arrojo un valor p= 0,031 en el tercio apical para el cemento MTA Fillapex. Con un valor de mediana de NaOCl= 3,0000, NaOCl + EDTA= 1,0000. Conclusiones: Al comparar los cementos obturadores MTA Fillapex, top seal y cemento de Grossman utilizando como irrigante NaOCl + EDTA se observo mayor penetracion del cemento de Grossman. A nivel del tercio apical se observo mayor penetracion con el cemento top seal. El cemento obturador MTA Fillapex presento mayor penetracion a nivel del tercio apical al utilizar como irrigante NaOCl EnglishBackground: the literature has shown that failed endodontic treatments are commonly due to the persistence of microorganisms. One important characteristic of root canal filling cements is their ability to penetrate the dentinal tubules, achieving an impermeable sealing between the dentinal walls and the central filling material, reducing potential filtrations and increasing the resistance to fracture. Objective: To evaluate through scanning electron microscopy (SEM) the penetration of MTA Fillapex, Grossman sealer and top seal all along the root canal. Methods: In vitro experimental study, in 36 human teeth randomly divided into 3 groups, (n= 12), which were prepared with the Step Back endodontic technique. Each group was divided into 2 subgroups using NaOCl 2.5%, and NaOCl 2.5% + EDTA 17% as irrigating solutions. The root canals were sealed using the lateral condensation technique, longitudinally sectioned to observe through scanning electron microscopy the cervical, medium and apical thirds, the penetration of the cement inside the dentinal tubules. The statistical analysis was performed with SPSS v22 IBM with p Results: through the Kruskal- Wallis test the Grossman sealer and top seal when using NaOCl + EDTA showed values of p= 0.025 and p= 0.002 in the medium and apical thirds respectively. The Mann-Whitney test showed a value of p= 0.031 in the apical third for the MTA Fillapex when using NaOCl. The median values were MTA Fillapex medium third= 2.000, apical third= 1.000; top seal medium and apical thirds= 4.000. Since the median values between the top seal and Grossman sealer were the same, the values from the variance were used, with a statistically significant result for the Grossman sealer= 0.276 in the medium third and top seal = 0.176 in the apical third. The Mann-Whitney test showed a value p= 0.031 in the apical third for the MTA Fillapex. With a median value of NaOCl= 3.000, NaOCl + EDTA= 1.000. Conclusions: When comparing the filling cements MTA Fillapex, top seal and Grossman sealer using NaOCl + EDTA as an irrigating solution, more penetration from the Grossman sealer was observed in medium third. At the apical third, more penetration from the top seal sealer was observed. The MTA Fillapex cement showed the greatest penetration at the apical third when using NaOCl as an irrigating solution.